Butter knife



FIG. 1 shows an overhead three-quarter perspective view of a butter knife;

FIG. 2 shows overhead plan view of a butter knife;

FIG. 3 shows a side view of a butter knife, the opposite side view being a mirror image thereof;

FIG. 4 shows an underside plan view of a butter knife; and,

FIG. 5 shows an underside three-quarter perspective view of a butter knife. 

CLAIM The ornamental design for a butter knife, as shown and described. 